徐深气田断裂发育及其对天然气成藏的控制作用

Fault development in Xushen gas field and its controlling effect on natural gas accumulation

为准确判断松辽盆地徐深气田断裂的发育及其与深层天然气成藏之间的关系,根据钻井、测井和分析测试资料,利用断裂生长指数、断裂活动速率、剖面伸展率及构造演化剖面,厘定徐深气田断裂主要活动时期、断裂系统等,并建立该区的天然气成藏模式。结果表明:徐深气田断裂主要活动时期由古至今依次为火石岭组、沙河子组、营一段、营三段、泉头组末—姚家组沉积时期;气田内断裂可划分为早期伸展断裂系统(Ⅰ)、早期走滑伸展断裂系统(Ⅱ)、晚期伸展断裂系统(Ⅲ)、晚期张扭断裂系统(Ⅳ)、早期走滑伸展—晚期伸展断裂系统(Ⅴ)、早期走滑伸展—晚期张扭断裂系统(Ⅵ)、走滑断裂系统(Ⅶ)(徐中、徐东)。Ⅴ、Ⅵ、Ⅶ型断裂系统是构成气源断裂的主要断裂系统类型。工业气流井均分布在距源断裂3 km范围内的火山岩区域内。

This paper delves into a more accurate determination of the relationship between the fault development of Xushen gas field and deep gas reservoir formation in Songliao Basin. The study draws on drilling, logging and test data, fault growth index, fault activity rate, section extension rate, and tectonic evolution sections and thereby produces the definition of the main active periods and the fault systems of Xujiaweizi fault and natural gas accumulation models of this field. The determination suggests that Xujia- weizi fault depression is composed of the main active periods： Huoshiling formation, Shahezi formation, Yingyi section, Yingsan section and late Quantou formation-Yaojia formation; the faults can be divided into seven systems： early extensional fault system （ Ⅰ ）, early strike-slip extensional fault system （ Ⅱ ）, late extensional fault system（ Ⅲ ）, late tenso-shear fault system（ Ⅳ ）, early strike-slip and late extension- al fault system （ Ⅴ ）, early strike-slip extensional and late tenso-shear fault system （ Ⅵ ）, and strike-slip fault system （ Ⅶ ） （ Xuzhong, Xudong）. Type Ⅴ, Ⅵ and Ⅶ are the main fault system types constituting gas source faults. Industrial gas wells are found evenly distributed in volcano rock region in the range of 3 kilometers from source faults.